The present invention relates to a flame-cutter for separating billets produced in a continuous caster wherein, during the separation process, the flame-cutter moves on a flame-cutting path in the direction of billet advance. The supply of oxygen for the flame-cutting process and, if desired, the heating flame supply are temporarily interrupted when the flame-cutter enters the region adjacent a support roller for the roller bed.
When a billet is cut by means of a flame-cutter, there is a tendency for the support rollers, on which the billet moves and on which it is supported over its entire width, to be damaged by the cutting process. To prevent such damage, each roller may be moved away from the billet by lowering it as the flame-cutter approaches the region in which the roller is located. However, the billet is then temporarily without support in the region where a roller has been withdrawn so that it is necessary for successive support rollers to be more closely spaced than would otherwise be the case. Moreover, the devices required to lower the support rollers are relatively expensive.
It is also known to substitute for the support rollers relatively short roller sections mounted on a shaft. The supporting width of a roller section takes up only a fraction of the width of the billet, and therefore the flame-cutter can cut the billet in the spaces between the supporting roller sections. This method has the disadvantage that complicated control devices are required, and the rollers may be damaged if for some unforeseen reasons the cutter deviates from its intended path.
A method which has the advantage of being relatively inexpensive is to temporarily interrupt the supply of flame-cutting oxygen in the region of a support roller in the roller bed and, if desired, also interrupt the supply to the heating flame. In this case, a normal roller bed with support rollers which support the slab can be operated without damaging the support rollers during the cutting process. A disadvantage to this method, as carried out prior to this invention, is that the grooves cut by the flame-cutter tend to vary in shape and, in particular, are wider than grooves cut where this method is not employed.